We were there from 27th April til 10th May, and we found the crowd levels excellent. It was our first trip to WDW, after numerous trips to DLP during very quiet times, so I was a bit anxious about long lines as none of us do well in crowds at all. However, the longest we waited was 25 mins for Astro Orbiter on Tues 9th because it had been closed first thing due to lightening in the area, and DS really wanted to ride it so we did it in the afternoon knowing it was the worst time.
We also used TGM, although we did not follow any strict plans, we used his general philosophy to great effect.
I would go again at this time of year in a heartbeat although it did get very hot towards the end of the holiday, it didn't bother us!
On Tuesday 9th in evening we walked straight on to Thunder Mtn 4 times in a row.